Apparatus for demonstrating the existence of magnetic lines of force



Oct. 10, 1950 2,524,804

J. W. IRBY APPARATUS FOR DEMONSTRATING THE EXISTENCE OF MAGNETIC LINES0F FORCE 2 Sheets-Sheet 1 Filed Feb. 2, 1949 w w j E m, I w Y A? r if 1Z "'I- f .57 4: I I iii/ /9 J n 0 o 0 d9 INVENTOR. Jfl/Wff 144 (f/75% BYOct. 10, 1950 J, w, Y 2,524,804

APPARATUS FOR DEMONSTRATING THE EXISTENCE 0F MAGNETIC LINES OF FORCEFiled Feb. 2, 1949 2 SheetsSheet 2 INVENTOR. JQM5WA V Patented Oct. 10,1950 APPARATUS FOR DEMONSTRATING THE EXISTENCE OF MAGNETIC LINES OFFORCE James W. Irby, Dayton, Ohio Application FebruaryZ, 1949, SerialNo. 74,166

(Granted under the act of March 3,1883, as

famendcd April 30, 1928; 370 0. G. 75'?) 4 Claims.

The invention described herein may be manufactured and used by or forthe United States Government for governmental purposes without paymentto me of any royalty thereon.

My invention relates generally to educational devices, and moreparticularly to instruction devices for demonstrating the existence andposition of magnetic lines of force between the poles of magnets, havingfor one of its objects the provision of a compact, self-containededucational or demonstration kit with a permanent magnet, and keepermeans for the magnet movable to and from operative contacting positionacross the poles of the magnet, together with transparent, substantiallyrigid, envelope means containing finely divided iron particles orferrous powder, and supporting means for holding the magnet and envelopemeans in cooperative demonstrating position, with the envelopedisposed.horizontally above the magnet or in non-operative position inspaced relation to the poles of the magnet while the keeper means is incontact with the poles of the magnet.

A further object of myinvention is the provision of sealed envelope orcontainer means having spaced non-metallic, parallel, transparent sidewalls, enclosing a quantity of finely divided ferrous particles andsupporting means fixed with respect to the magnet means for rigidlysupporting the relation above the poles of the magnet, and hingedsupporting means, swingable relative to the magnet means, having keepermeans mounted thereon for yieldable contacting engagement with the polesof the magnet when the hinged supporting means is swung in onedirection, and means on the hinged supporting means for supporting theenvelope in predetermined spaced relation to the poles of the magnetwhen the keeper means is in contact with the poles of the magnet.

Other objects and advantages of the invention will become apparent fromthe following description taken in connection with the accompanyingdrawings, in which like reference characters refer to like parts in theseveral figures.

Drawings envelope means in juxtaposed horizontal taken approximately onthe plane indicated by line 2-2 in Fig. 1, illustrating the cover inclosed position with the keeper means in contact with the poles of themagnet and the transparent envelope retained within the cover, inspaced, parallel, non-operative relation to the poles of the magnets.

Fig. 3 is a perspective view of my demonstrating apparatus, with thecover removed, and the transparent envelope in the operative positionabove the poles of the magnets.

In the drawing the reference numeral I denotes a rectangular case or boxof wood or other suitable material having front and rear end walls 2 and3, and opposite side walls 4 and 5, a rectangular cover 6 beingprovided, hinged to the case I at l, the cover 6 having front and rearend walls 8 audit, side walls It and II, and a top closure panel l2.

Located within the case I, downwardly spaced below the top edges of thefront and rear end walls 2 and 3 and the side walls 4 and 5, is ahorizontally disposed non-metallic magnet supporting panel 13 on which apair of permanent horse shoe magnets M and it are secured, theirrespective magnetic poles Ito and Ho facing each other in relativelyspaced relation. One or both of the magnets M and 15 may be mounted forindividual relative adjustment if desired. The upper side faces of themagnets are preferably disposed to lie in the same horizontal plane,parallel to the supporting panel 93. A collapsible corner brace It isprovided for supporting the cover 6 in open or raised position as shownin Fig. 1 of the drawings, latch members [i being fixed on front wall ofthe base or box l for latching'engagement with cooperating latch keepersor shoulder projections Ila, fixed on the front wall of the cover or lid6, to hold the cover tightly closed.

A keeper supporting panel i3 is provided, preferably narrower than thedistance between the side walls iii and H of the cover, the panel l8being hinged at one edge to the inner face of the rear wall 9 at spacedpoints 59, in spaced parallel relation to the under side of the top E2,the panel l8 being thus supported at one edge by the hinges l9, and atthe opposite edge by a ledge or strip 2t, secured to the under side ofthe top [2, in spaced parallel relation to the front wall 8. Retainermeans is provided for the keeper panel 18, comprising a centrallypivoted bar 2!, pivoted at 22 on theledge member 2B, the bar 2i, andcover 5 forming means for lifting and retaining the keeper panel itwithin the cover 6, when the cover is raised, and in operative positionwhen the cover is closed.

Secured to the keeper panel 6, directly above the poles Ma and l5a ofthe magnets l4 and 15, when the cover is closed, are a pair of spacedparallel rectangular blocks 23 and 24. Superimposed on the blocks 23 and24 are sponge rubber pads 23a and 24a, upon which are mounted soft iron"keeper plates 25 and 26 for the respective magnets l4 and I5, providingyieldable supporting means to resiliently urge the keepers into firmcontact with the poles of the magnets when the cover 6 is closed, asshown in Fig. 2 of the drawings. Each of the keepers 25, 26 is aperturedat longitudinally spaced points to loosely receive a pair of headedretainer screws 27, secured in the blocks 23, 24 with the heads of thescrews limiting the outward movement of the keeper plates when the cover6 is raised as shown in Fig. 1, the screws 2! being positioned to liebetween the spaced extremities of the magnets I4 and I5 when the cover 6is closed.

The space between the keeper panel 18 and the top l2 receives atransparent sealed envelope 29, as best seen in Fig. 2, and describedlater in detail, the keeper panel l8 constituting means for retainingthe envelope 29 within the cover in predetermined spaced relation to themagnets l 4-i 5 when the cover is closed, a spacing strip 30 extendingalong one side of the cover limits the lateral shifting of the envelope29, while the ledge strip retains the envelope 29 against relativeshifting in the transverse plane.

A pair of supporting strips or ledges 3! and 32 are secured along theopposite side walls 4 and 5 of the base I, below the upper edges thereofat a distance substantially equal to the thickness of the envelope 29 sothat when the envelope 29 is deposited on the ledges 3| and 32 the lowersurface of the envelope is in juxtaposed horizontal position above thepoles of the magnets, preferably in closely spaced relation to the upperside faces of the magnets, permitting the envelope 29 to be shifted oroscillated on the ledges 3! and 32 without striking or scraping thesides of the magnets.

The transparent envelope, as best seen in Fig. 2, comprises upper andlower panels or plates 33 and 34 of rigid thin non-metallic sheetmaterial, such as glass or Plexiglas, the sheets being spaced apart inparallel relation at their edges and sealed by an annular strip 35,preferably of the same material. The space 36 between the plates 33 and34 contains a predetermined quantity of finely divided ferrousparticles, as indicated at 3'5, such as soft iron filings or ironpowder, the quantity being sufi'icient to substantially cover at least amajor portion of the inner surface of the lower plate 34 when thepowdered material is uniformly spread while the plates are in horizontalposition. At least one of the plates is transparent so that the ferrousparticles or powder 36 can be observed therethrough, when the envelopeis in demonstrating position above the poles 14a and l5a of the magnets.

In demonstrating the existence, position, and direction of the magneticlines of force in fields of the magnets l4 and I5, the cover 6 is firstraised as shown in Fig. 1 to lift the keepers and 26 from the poles Maand l5a of the magnets !4 and I5. The keeper supporting panel I8 is thenreelased and temporarily swings downwardly to release the envelope 29.The envelope 29 is then removed and deposited onto the rails or supports3| and 32, directly above magnets,

with the transparent plate facing upwardly, the keeper supporting panel[8 being again latched in position within the cover 6. The envelope 29may be manipulated or shaken either before or after placing the same onthe rails 3|, 32 to spread the iron particles as uniformly as possibleover the envelope surface. The iron particles will be attracted to formthe usual patterns demonstrating the existence of the magnetic lines offorce, well known in physics, as illustrated in the well knownexperiment or demonstration in which iron filings are poured on thesurface of a sheet of paper resting on the poles of a magnet and thepaper is shaken.

My transparent envelope however, having the loose iron particles sealedtherein between the two parallel non-metallic plane surfaces or plates,eliminates any buckling, bending, or snapping of the supporting surfacefor the fine particles, which usually occurs when a single flexiblesheet is employed, and it is not possible to spill or lose any of theferrous particles, nor can they spill onto the surface of the magnets,making their removal difficult and time consuming. My improveddemonstrating device, or kit, can be rapidly set up, the demonstrationcompleted, and the apparatus quickly closed with no danger or spillingor loss of the ferrous material, and no appreciable reduction in themagnetism in the magnets during use or storage can occur, due to theautomatically replaceable keepers for the magnets when the cover isclosed while the device is not in use.

I claim:

1. In an educational device for demonstrating the position and extent oflines of force of a magnet, a rectangular box-like casing having ahinged cover, a horizontal support within the casing, a magnet mountedhorizontally on the support next to the same, a magnet keeper yieldablymounted on the hinged cover in yieldable contacting engagement with thepoles of the magnet when the cover is closed on the casing, and movablewith the cover to a spaced, out of the way position relative to thepoles of the magnet, a substantially rigid thin box-like envelope ofnon-magnetic material having spaced parallel side walls, at least one ofsaid side walls being transparent, a quantity of finely dividedmagnetically attractable particles sealed within the box-like envelope,in sufficient quanttiy to at least uniformly cover a major portion ofthe bottom of the envelope when the lower side wall of the envelope ishorizontal, and means on the horizontal support for fixedly supportingthe said envelope thereon with the transparent side wall uppermost andthe opposite side wall in horizontal juxtaposed relation above the polesof the magnet.

2. In an educational device, a rectangular casing, a rectangular coverhinged thereto, a magnet supporting panel disposed within the casing andspaced below the top edge thereof, a permanent magnet fixed to thesupporting panel with its magnetic poles in juxtaposed parallel relationto the panel, a keeper panel hinged within the cover in spaced relationto the magnet supporting panel and the poles of the magnet, a metallickeeper yieldably mounted on keeper panel for yieldable contactingengagement with the poles of the magnet when the cover is closed, a pairof spaced parallel transparent plates including spacing meanstherebetween extending around the edges to form a sealing enclosure, aquantity of finely divided iron particles loosely disposed between thetransparent plates sufiicient to at least partly uniformly cover thesurface of one of the side plates when the envelope is horizontal,spaced parallel supporting ledges fixed on the opposite sides of theinterior of the casing above the magnet supporting panel to support thetransparent envelope within the casing in juxtaposed relation above themagnet and parallel to the said magnet supporting panel.

3. Apparatus as claimed in claim 2 including transparent envelopesupporting and retaining means carried by the interior of the coverbetween the inner surface of the cover and the keeper supporting panelfor rigidly supporting the envelope between the interior of the coverand the keeper panel, with the keeper in contacting engagement with thepoles of the magnet.

4. In an educational device for demonstrating the existence of amagnetic field of a magnet, the combination of a panel support, apermanent magnet fixed on the panel support with its magnetic polesdisposed next to the panel support in parallel relation thereto,metallic keeper means for the magnet, a keeper supporting panelpivotally connected to the panel support to swing toward and away fromthe poles of the magnet, resilient mounting means on the keepersupporting panel yieldably mounting the keeper in contacting engagementwith the poles of the magnet when the keeper panel is swung toward themagnet, and a substantially rigid rectangular envelope comprising a pairof spaced parallel thin fiat non-metallic side plates one of which istransparent, sealing and spacing means extending between and around theedges of the flat plates to close and seal the space between theadjacent side plates, an appreciable quantity of finely divided ironparticles loosely deposited within the closed space between the sideplate, and means for supporting the envelope rigidly relative to thepanel support for the magnet with one of the flat plates of the envelopein closely spaced adjacent relation to the poles of the magnet and in ahorizontal position, whereby the pat tern formed by the iron particlesbetween the poles of the magnet can be observed from above, through thetransparent side plate, and means for supporting the transparentenvelope in a predetermined non-operative position spaced from the polesof the magnet and parallel to the keeper supporting panel, when themagnet keepers means is in contact with the poles of the magnet.

JAMES W. IRBY.

REFERENCES CITED The following references are of record in the file ofthis patent:

Catalogue of Scientific InstrumentsL. E. Knott Apparatus Co., Boston.Pages 279-280.

